2108 PRELIMS Flashcards
Why do we have to do maintenance?
“The maintenance of an aircraft provides assurance of
flight safety, reliability, and airworthiness.”
Why Aircraft Maintenance is Important
- Avoiding lost flights because of failure.
- Maintaining good performance.
- Ensuring passenger safety.
-Extending the life of the aircraft.
If you want to make sure that everything is in its perfect condition, schedule regular aircraft maintenance
and replacement of damaged parts in accordance with aircraft performance manuals from the relevant
manufacturers.
Avoiding lost flights because of failure.
Regular maintenance will ensure that the aircraft is serviceable for the time it flies. Operational checks
before every flight will make sure that failure does not occur before any trip.
Maintaining good performance.
Passenger safety is the priority of any airline, and through regular maintenance and checks, we will assure
that the travel of those passengers will be undertaken in the safest and smoothest way possible.
Ensuring passenger safety.
However, all types of aircraft will have one standard maintenance procedure, which you should
carry out WHEN
before every flight
Regular maintenance will extend aircraft life and ensure that aircraft will perform safely for the expected
period of time.
Extending the life of the aircraft.
The role of an aircraft engineer
involves the application of scientific and technological principles to the research, development and design of aircraft and their components.
The Role of the Mechanic
Aircraft mechanics perform inspections, make repairs and perform scheduled maintenance of aircraft. They
have the ability to diagnose both electrical and mechanical problems and identify repair procedures.
Two types of Maintenance
Preventive maintenance and Corrective maintenance
usually performed at regular intervals. This is done to prevent deterioration of the system to an unusable level and to keep it in operational condition.
preventive maintenance
It is sometimes referred as scheduled maintenance.
preventive maintenance
every when is preventive maintenance held
This could be daily, every flight, every 200 flight hours, or every 100 cycles (a cycle is a takeoff and a landing.)
Since these breakdowns occur at various, unpredictable intervals, the maintenance actions employed to correct the problem are referred to as
corrective maintenance
corrective maintenance is also called
unscheduled maintenance
goals of an airline maintenance program
- To deliver airworthy vehicles to the flight department in time to meet the flight schedule
- To deliver these vehicles with all necessary maintenance actions completed or properly deferred
The objectives of an airline in-service maintenance program are as follows:
1) To ensure the realization of the inherent safety and reliability levels of the equipment
2) To restore safety and reliability to their inherent levels when deterioration has occurred
3) To obtain the information necessary for adjustment and optimization of the maintenance program when these inherent levels are not met
4) To obtain the information necessary for design improvement of those items whose inherent reliability proves inadequate
5) To accomplish these objectives at a minimum total cost, including the costs of maintenance and the cost of residual failures
The maintenance programs currently in use in commercial aviation were developed by the industry using
two basic approaches:
process oriented approach and the task oriented approach.
difference between process oriented approach and task oriented approach
(a) the attitude toward maintenance actions and
(b) the manner in which maintenance actions are determined and assigned to components and systems.
process-oriented approach
Hard time(HT)
On- condition (OC)
Condition monitoring (CM)
are for components Or systems that have definite life Limits or detectable wear out periods.
hard time and on-condition
are operated to failure and failure rates are tracked to aid future prediction or failure rate prevention.
condition monitoring
task-oriented approach
Uses pre determined tasks to avoid in- service failures
Rebundancy and reliability programs utilized.
is a failure preventive process which requires that the item be removed from the vehicle and either completely overhauled, partially overhauled (restored), or discarded before exceeding the specified interval.
Hard time
The hard time interval may be specified by
calendar time, by engine or airplane check interval (engine change, “C” check, etc.), by landing or operating cycles, by flight hours, by block hours, by specified flights (over water, terminating, etc.), or in conjunction with another
process
must be restricted to components, equipment, or systems on which a determination of continued airworthiness may be made by measurements, tests, or other means without doing a tear-down inspection. These on condition checks are to be performed within the time limits (intervals) prescribed for each OC check.
on-condition
involves the monitoring of the failure rates, removals, etc. of individual components or systems that do not have a definite lifetime or a noticeable wear-out period.
condition monitoring process
are operated until failure occurs and replacement of
CM items is an unscheduled maintenance action.
CM components
MSG-1 was first published in
1968
MSG-1 was used for developing scheduled maintenance for
B747
process orientated and used a bottom-up approach. It also introduced ‘condition monitored maintenance’ concept.
MSG-2
the original version of MSG-3 was first published in
1980
MSG-3 introduced
top-down approach by focusing on ‘consequences of failure’.
MSG-3 expected the assessment of functional failures and the assignment of the consequences of those failures into two basic categories,
Safety and Economic
is a document developed by the Airlines For America (A4A) (formerly ATA).
MSG-3 (Maintenance Steering Group) ‘Operator/Manufacturer Scheduled Maintenance Development’
‘Operator/Manufacturer Scheduled Maintenance Development’ aims to present
methodology to be used for developing scheduled maintenance tasks and intervals, which will be acceptable to the regulatory authorities, the operators and the manufacturers.
The main idea behind ‘Operator/Manufacturer Scheduled Maintenance Development’ concept
recognise the inherent reliability of aircraft systems and components, avoid unnecessary maintenance tasks and achieve increased efficiency.
underlying principles of MSG-3
Maintenance only effective if task applicable
No improvement in reliability by excessive maintenance
Needless tasks can also introduce human error
Few complex items exhibit wear out
Monitoring generally more effective than hard-time overhaul - Condition-based maintenance
(sometimes known as CBM)
Reliability only improved by modification
Maintenance may not be needed if failure cheaper
The basic goal of MSG-3
identify maintenance tasks which are both effective and efficient in enabling a new aircraft to be designed and operated in a manner which achieves a satisfactory level of safety and reliability throughout its life.
process of MSG-3
(1)Systems and Powerplant (including components and APUs)
(2) Aircraft Structures
(3) Zonal Inspections
(4) Lightning/High Intensity Radio Frequency (L/HIRF).
MSG-3 is widely used to develop initial maintenance requirements for modern commercial aircraft which are published as a
Maintenance Review Board Report (MRBR).
FOUR SECTIONS OF MSG3
(1) Systems and Powerplant (including components and APUs)
(2) Aircraft Structures
(3) Zonal Inspections
(4) Lightning/High Intensity Radio Frequency (L/HIRF).
